The United States has charged two Chinese men it says hacked the computer systems of companies and government agencies in a dozen countries, in what Washington says was a wide-reaching state-backed campaign of cyber-espionage.
NASA and the US Navy were among those allegedly targeted in a programme the US Justice Department said also hit a major bank, telecom companies and healthcare providers in 12 countries.
The charges drew a furious response from Beijing, which accused Washington of "fabricating facts".
Deputy Attorney General Rod Rosenstein said China had repeatedly broken President Xi Jinping's 2015 pledge to halt cyberattacks on US companies and commercial infrastructure.
"It is unacceptable that we continue to uncover cybercrime committed by China against other nations," he said.
"We want China to cease its illegal cyber activities and honour its commitment to the international community.
"But the evidence suggests that China may not intend to live up to its promises."